A morphological and functional study on antigen binding and endocytosis by immunocytes

Area of Science:

• Immunology
• Cell Biology

Background:

• Lymph node cells play a crucial role in immune responses.
• Antigen uptake and processing are key events in adaptive immunity.

Purpose of the Study:

• To investigate antigen binding and endocytosis by rat lymph node cells.
• To characterize the cell types involved in antigen binding and endocytosis.
• To determine the effect of antigen endocytosis on antibody production.

Main Methods:

• Immunoenzymatic techniques for antigen binding and endocytosis studies.
• Double staining for surface antigen and intracytoplasmic antibody detection.
• Ultrastructural studies using peroxidase as antigen.
• Local hemolysis plaque assay and biosynthetic labeling for antibody synthesis and secretion analysis.

Main Results:

• Antigen-binding cell numbers varied with antigen type, time post-immunization, and booster injections.
• In secondary responses, 80% of antigen-binding cells were proplasmocytes and plasmocytes, with 82% containing surface antigen and intracytoplasmic antibodies.
• Endocytosed antigen was localized in cytoplasmic compartments, excluding the Golgi apparatus cisternae involved in antibody synthesis.
• Antigen endocytosis did not affect antibody secretion or synthesis.

Conclusions:

• Rat lymph node cells, particularly plasma cells, actively bind and internalize antigens.
• Antigen uptake occurs in various cytoplasmic compartments but does not directly influence the Golgi apparatus's antibody synthesis function.
• Endocytosis of antigen does not modulate the rate of antibody secretion or synthesis.